< But the question still remains...why did things fail after a bump in the road when entering alley?  Maybe we need Inspector Columbo!!...he was always good at this kind of stuff.  (Actually for me as a bone-head novice mechanic, it's super cool to witness experts attacking the problem from multiple angles.) >

Not a master mechanic here, but a sometimes wannabe Columbo – observing that Alistair’s original description of the problem said nothing about a bump in the road.  That was introduced by a response that possibly a turn into an alley involved a bump and then several have speculated about what the bump did.  Speculations about the speculative bump.